question_answer

\[R-\underset{\begin{smallmatrix}  || \\  O \end{smallmatrix}}{\mathop{C}}\,-Cl+{{H}_{2}}\xrightarrow[S]{Pd/BaS{{O}_{4}}}RCHO\], the name of reaction is:

A)  Cannizaro reaction

B)  Rosenmund reduction

C)  Clemmensen reduction

D)  Wolff-Kishner reduction

Correct Answer: B

Solution :

Cannizaros reaction: The compound which does not contain \[\alpha \]-hydrogen atom, undergoes self oxidation-reduction when reacted with 50% aqueous or ethanolic alkali at room temperature. \[\underset{formaldehyde}{\mathop{2HCHO}}\,+{{H}_{2}}\xrightarrow{Pd/BaS{{O}_{4}}}\underset{sod.\text{ }formate}{\mathop{HCOONa}}\,\]\[\underset{methanol}{\mathop{+C{{H}_{3}}OH}}\,\] Rosenmunds reduction: Acid chlorides when reduced by hydrogen in boiling xylene in presence of \[Pd/BaS{{O}_{4}}\], gives aldehyde in good yield. \[\underset{acyl\text{ }chloride}{\mathop{RCOCl}}\,+{{H}_{2}}\xrightarrow{Pd/BaS{{O}_{4}}}\underset{aldehyde}{\mathop{RCHO}}\,\] Clenunensens reduction: It is commonly employed for reducing carbonyl group into methylene group. Wolff-Kishner reduction: It is reduction of hydrazones, semicarbazones, or azines of aldehydes and ketones to hydrocarbons in vigorously basic conditions \[({{C}_{2}}{{H}_{5}}ONa)\]or NaOH) with the evolution of nitrogen. \[\underset{ketone}{\mathop{{{R}_{2}}C=O}}\,+{{H}_{2}}N\,N{{H}_{2}}\xrightarrow{{}}\underset{hydrazone}{\mathop{{{R}_{2}}C=N\,\,.\,\,N{{H}_{2}}}}\,\]